Long exposure HDR photo from Canary Islands

Today I would like to share with you a photo I took a few minutes before sunrise on Fuerteventura island. The longest exposure was 247 seconds, taking whole sequence of 5 photos took more than 7 minutes! For that reason I had only one chance to take this photo. A few minutes earlier it was too dark, a few minutes later it was too light.

I'm pretty happy with the results although I'm thinking of reprocessing this image.

EXIF data:
Camera: Canon 50D
Lens: Canon 10-22 f/3.5-4.5 USM
Focal length: 10 mm
Aperture: f/11.0
Exposure time: 60 s ("middle" exposure)
ISO: 100
Number of exposures: 5
E.V. Step: 1 EV
Flash used: no
Tripod used: yes
Filters used: ND8
Software: Magic Lantern 2.3, Photomatix Pro 4.2.5 (Details Enhancer), Lightroom 4.2, Photoshop CS6